The development of porcine oocytes from large (3.1–8.0 mm in diameter) or small (<3.1 mm) follicles was examined after maturation culture in medium containing porcine follicular fluid (pFF). Large follicles yielded larger (256 m v . 221 m; P <0.05) cumulus–oocyte complexes and more (22 v . 14%) morphologically normal oocytes than small follicles (Experiment 1). In Experiments 2–4, maturation media supplemented with mixed pFF (10%) from small and large follicles was used. More oocytes from large follicles matured (58% v . 91%), formed pronuclei (81% v . 90%) and developed to the blastocyst stage (2% v . 10%) than oocytes from small follicles. In Experiments 5–7, the effects of pFF collected from either small or large follicles on oocyte development were examined. Regardless of the source of oocytes, large-follicle-derived pFF more significantly enhanced preimplantation development than did small-follicle-derived pFF. The highest rate of blastocyst formation (16%) was found when oocytes from large follicles were cultured in maturation medium containing large-follicle-derived pFF. These results suggest that oocytes from large follicles have greater developmental potential than oocytes from small follicles, and that the origin of pFF, which is added to the maturation media, might be an important factor for improving in vitro development of porcine oocytes.

The purpose of this study was to examine the effects of alpha-linolenic acid (ALA) treatment during in vitro maturation (IVM) on nuclear maturation, intraoocyte glutathione (GSH) content, meiotic progression, and developmental competence after parthenogenesis (PA) and somatic cell nuclear transfer (SCNT) in pigs. Medium-199 containing 10% (vol/vol) porcine follicular fluid (PFF; PPF control) or 0.4% (wt/vol) fatty acid-free BSA (BSA control) was used for IVM. The proportion of oocytes reaching the metaphase II (MII) stage was not influenced by ALA treatment at various concentrations (50, 100, and 200 μM). However, treatment with 100 μM ALA significantly increased (P < 0.05) intraoocyte GSH content (1.19 vs. 1.00 and 0.92 pixels per oocyte, comparing the treated oocytes, BSA control, and PFF control, respectively) and embryonic development to the blastocyst stage after PA (47.1 vs. 35.5 and 35.2%) and SCNT (31.4 vs. 23.9 and 24.3%). ALA treatment (100 μM) accelerated oocyte maturation, and a higher proportion of ALA-treated oocytes (89.6%) reached the MII stage than did the untreated controls (75.5%) at 33 h of IVM. Mitogen-activated protein kinase kinase inhibitor (U0126) treatment during IVM inhibited nuclear maturation and embryonic development after PA. However, 100 μM ALA completely counteracted the suppressive effect of U0126 on nuclear maturation and partially counteracted the effect on blastocyst formation. Our results demonstrate that treatment with 100 μM ALA during IVM improves developmental competence by accelerating nuclear maturation and also influencing cytoplasmic maturation, such as increased GSH content in IVM oocytes.

Lee J, et al. J Vet Sci. 2015 Sep;16(3):373-380. https://doi.org/10.4142/jvs.2015.16.3.373